Modern aircraft have a variety of flight control surfaces that can be controlled to maneuver the aircraft in flight. Seals are often provided at edges of movable flight control surfaces where they intersect with adjacent surfaces to reduce aerodynamic drag and noise.
One such type of flight control surface is the flaps on a passenger jet aircraft. Such aircraft are typically fitted with one or two sets of flaps on the trailing edge of each wing. These flaps are extendable along a direction of air flow over the wing. To reduce drag and noise caused by air rushing past the junctions of the flaps with the adjacent surfaces of the wings, bulb seals are provided at one of more edges of the flaps. Each bulb seal is made of a resilient material designed to be compressed by contact with another object when it is in its sealing position.
In conventional installations, the bulb seal is coupled to a bracket which is in turn mounted to the aircraft with screws or other suitable fastening arrangement. The bracket has a channel, and the seal has a corresponding mounting portion shaped to be slid into the channel for mounting. To prevent the seal from migrating out of the channel, it is fixed in place, typically using safety wire that must be threaded through holes in the seal and the bracket and then twisted together like a bread tie.
Over time, this safety wire connection tends to wear and eventually breaks, typically without notice. When a broken safety wire on an air seal is observed, it can be cause for a flight delay, which is very expensive.